无法将图像（字节数组）从表转换为多部分文件 Spring mvc

Question

问题：无法将字节转换为多部分文件，我使用自定义多部分文件来包装字节、名称、大小、内容类型。图像存储在目标部分，但不显示在前端。 日志中没有错误。谁能帮我解决这个问题。

自定义多部分文件。

    public class BASE64DecodedMultipartFile implements MultipartFile {
    private final byte[] imgContent;
    private String contentType;
    private String originalFilename;
    private String destPath = System.getProperty("java.io.tmpdir");

    private FileOutputStream fileOutputStream;

    public File getFile() {
        return file;
    }

    public void setFile(File file) {
        this.file = file;
    }

    private File file;
    private long size;

    public BASE64DecodedMultipartFile(byte[] imgContent, String contentType,String originalFilename,String path,long size) {
        this.imgContent = imgContent;
        this.contentType=contentType;
        this.originalFilename=originalFilename;
        file = new File(destPath + originalFilename);
        this.size=size;
    }
    @Override
    public String getName() {
        return "picture";
    }

    @Override
    public String getOriginalFilename() {
        return originalFilename;
    }

    @Override
    public String getContentType() {
        return contentType;
    }

    @Override
    public boolean isEmpty() {
        return false;
    }

    @Override
    public long getSize() {
        return size;
    }

    @Override
    public byte[] getBytes() throws IOException {
        return imgContent;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(imgContent);
    }

    @Override
    public void transferTo(File file) throws IOException, IllegalStateException {
        fileOutputStream = new FileOutputStream(file);
        fileOutputStream.write(imgContent);
    }
}

使用自定义的 Multipart 文件如下。

 BASE64DecodedMultipartFile bASE64DecodedMultipartFile=new BASE64DecodedMultipartFile(imgbytes,"image/png","pleasure image 1.png",path,527110);
 
        bASE64DecodedMultipartFile.transferTo(bASE64DecodedMultipartFile.getFile());

//以视图发送的形式存储。 form.setPicture(bASE64DecodedMultipartFile);

JSP 页面：

<div class="col-sm-9">

我没有在 UI 中获取图像内容： enter image description here

Answer 1

最近我试图从 bytearray 转换为 multipart，我能够实现这一点，但我不知道这种方法是否好（欢迎提出建议）

1. Pojo 类获取属性文件

    @ConfigurationProperties(prefix = "file")
       public class FileStorageProperties {
           private String uploadDir;
   
           public String getUploadDir() {
               return uploadDir;
           }
   
           public void setUploadDir(String uploadDir) {
               this.uploadDir = uploadDir;
           }
       }
   

2. 控制器

   @RestController 公共类 FileController {

     private static final Logger logger = LoggerFactory.getLogger(FileController.class);
   
     @Autowired
     private FileStorageService fileStorageService;
   
     @PostMapping("/uploadFile")
     public UploadFileResponse uploadFile(@RequestParam(value = "image") base64Str: String, fileName: String?) {
         String fileName = fileStorageService.storeFile(Base64DecodedMultipartFile(Base64.getMimeDecoder().decode(base64Str),fileName));
   
         String fileDownloadUri = ServletUriComponentsBuilder.fromCurrentContextPath()
                 .path("/downloadFile/")
                 .path(fileName)
                 .toUriString();
   
         return new UploadFileResponse(fileName, fileDownloadUri,
                 file.getContentType(), file.getSize());
     }
   
     @PostMapping("/uploadMultipleFiles")
     public List<UploadFileResponse> uploadMultipleFiles(@RequestParam("files") MultipartFile[] files) {
         return Arrays.asList(files)
                 .stream()
                 .map(file -> uploadFile(file))
                 .collect(Collectors.toList());
     }
   
     @GetMapping("/downloadFile/{fileName:.+}")
     public ResponseEntity<Resource> downloadFile(@PathVariable String fileName, HttpServletRequest request) {
         // Load file as Resource
         Resource resource = fileStorageService.loadFileAsResource(fileName);
   
         // Try to determine file's content type
         String contentType = null;
         try {
             contentType = request.getServletContext().getMimeType(resource.getFile().getAbsolutePath());
         } catch (IOException ex) {
             logger.info("Could not determine file type.");
         }
   
         // Fallback to the default content type if type could not be determined
         if(contentType == null) {
             contentType = "application/octet-stream";
         }
   
         return ResponseEntity.ok()
                 .contentType(MediaType.parseMediaType(contentType))
                 .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
                 .body(resource);
     }
   

   }

3. 服务类

     @Service
     public class FileStorageService {
   
         private final Path fileStorageLocation;
   
         @Autowired
         public FileStorageService(FileStorageProperties fileStorageProperties) {
             this.fileStorageLocation = Paths.get(fileStorageProperties.getUploadDir())
                     .toAbsolutePath().normalize();
   
             try {
                 Files.createDirectories(this.fileStorageLocation);
             } catch (Exception ex) {
                 throw new FileStorageException("Could not create the directory where the uploaded files will be stored.", ex);
             }
         }
   
         public String storeFile(MultipartFile file) {
             // Normalize file name
             String fileName = StringUtils.cleanPath(file.getOriginalFilename());
   
             try {
                 // Check if the file's name contains invalid characters
                 if(fileName.contains("..")) {
                     throw new FileStorageException("Sorry! Filename contains invalid path sequence " + fileName);
                 }
   
                 // Copy file to the target location (Replacing existing file with the same name)
                 Path targetLocation = this.fileStorageLocation.resolve(fileName);
                 Files.copy(file.getInputStream(), targetLocation, StandardCopyOption.REPLACE_EXISTING);
   
                 return fileName;
             } catch (IOException ex) {
                 throw new FileStorageException("Could not store file " + fileName + ". Please try again!", ex);
             }
         }
   
         public Resource loadFileAsResource(String fileName) {
             try {
                 Path filePath = this.fileStorageLocation.resolve(fileName).normalize();
                 Resource resource = new UrlResource(filePath.toUri());
                 if(resource.exists()) {
                     return resource;
                 } else {
                     throw new MyFileNotFoundException("File not found " + fileName);
                 }
             } catch (MalformedURLException ex) {
                 throw new MyFileNotFoundException("File not found " + fileName, ex);
             }
         }
     }
   

     MultipartFile implemetation 
    
class Base64DecodedMultipartFile implements MultipartFile {

    private Byte[] image;
    private String fileName;

    public Base64DecodedMultipartFiles(Byte[] image, String fileName) {
        this.image = image;
        this.fileName = fileName;
    }

    @Override
    public String getName() {
        return "picture";
    }

    @Override
    public String getOriginalFilename() {
        return fileName;
    }

    @Override
    public String getContentType() {
        return MediaType.MULTIPART_FORM_DATA_VALUE;
    }

    @Override
    public boolean isEmpty() {
        return false;
    }

    @Override
    public long getSize() {
        return image.length;
    }

    @Override
    public byte[] getBytes() throws IOException {
        return image;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(image);
    }

    @Override
    public void transferTo(File file) throws IOException, IllegalStateException {
       new FileOutputStream(file).write(image);
    }
}

在 multpartFile 实现中，您可以根据需要自定义，文件上传可以参考this